In recent years, mail ordering has become increasingly common. In order to cope with the increased need for packaging mail ordered items, different systems and methods for automatically forming packaging boxes have been proposed.
US 2008 0020916 A1 discloses a box-making machine, which executes creasing and cutting steps to obtain a cardboard blank, which is then folded to obtain a packaging box from the blank. The embodiments described herein may be advantageously used in this type and similar types of machines.
For making cardboard blanks to be used in box-making machines, usually a long web of cardboard is fed to such machine either from a roll of corrugated cardboard or from a stack, in which the web is zigzag folded into panels. Corrugated cardboard from a roll is flexible in one direction, as it comprises only one flat layer to which a corrugated layer is attached. Such type of corrugated cardboard is called hereinafter “single-faced corrugated cardboard” and, while it has a certain thickness and is hence a three-dimensional body, only the two main surfaces are addressed as “sides”, namely the so called “closed side”, to which the flat layer is attached, and the open side, which shows the corrugated structure.
Without special measures or treatment, single-faced corrugated cardboard is not well suited for making packaging boxes. Hence, so called “standard” corrugated cardboard, which is rather stiff as it comprises a corrugated layer sandwiched between two flat layers, is preferred for making packaging boxes. However, such cardboard cannot be stored on a roll and hence is usually provided in form of a stack of zigzag folded panels. US 2013 0210 597 A1 discloses a machine for creating blanks from zigzag folded panels provided from different stacks.
Zigzag folded cardboard has the disadvantage that there are transversal folds in the source material at the positions where the panels are connected. These folds are usually not at positions where folds are needed in a blank that is to be cut from the source material. This is especially the case, when the sizes of the blanks to be cut vary while the panels in a stack of cardboard have a fixed size.
Avoiding the situation where a fold in the source material will appear in the blank limits the maximum blank size (namely, limited to the distance between two folds), and causes an undesired amount of waste material. When such folds are present in a blank that is used to fold a piece of packaging such as a box, there is a risk that the blank will not be folded at the intended crease lines, but at the folds that are already present in the source material. This may cause undesired effects during or after the fold process and may cause crashes and/or damage to the packaging and/or item(s) being packed or result in an undesired appearance of the packaging and/or insufficient protection of the item(s) inside the packaging.
WO 2014 188010 A1 proposes an apparatus and a method that allow rigidifying cardboard having at least one fold and obtaining packaging material with increased stiffness from a cardboard stack that is formed by zigzag folding a cardboard web into panels connected via transverse folds, by applying creasing means to form in particular line-shaped indentations on at least one side of said cardboard, wherein at least some of said indentations intersect said at least one fold. This apparatus and method purportedly advantageously improve the production of cardboard boxes using cardboard from a stack of a zigzag folded cardboard web with transverse folds in respect of preciseness and/or stability of the cardboard boxes.
However, while the apparatus and method disclosed in WO 2014 188010 A1 work perfectly well in many cases, just forming indentions that intersect the unwanted folds may not in all cases lead to sufficient stiffness, in particular when rather thin material is used and/or the formed boxes are rather big and/or items to be packaged in said boxes are rather heavy.
WO 2014 119 439 A1 discloses different methods for creating standard corrugated cardboard having at least one corrugated layer sandwiched between two flat layers on or at the site of a system for automatically forming packaging boxes. According to one of the methods, single-faced corrugated cardboard from a roll is provided and a second flat layer is glued to it. Another method comprises forming a corrugated layer on-site and gluing two flat layers onto opposite sides of the thus created corrugated layer. However, it has turned out in practice that the gluing unit needed for applying glue to the respective layers on-site is rather complex, costly and requires a lot of maintenance.
WO 2014 119439 A1 also discloses a method of forming so-called “double corrugated” cardboard, in which the corrugated sides of two single-faced corrugated cardboards are brought into engagement with each other with little or no glue. However, it has turned out that without glue the cohesion between the two single-faced cardboards is not sufficient. Moreover, double-corrugated cardboard with two corrugated layers means using a lot of material, which not only increases costs and weight of the packaging boxes formed therefrom, but also increases waste.
In order to improve creating corrugated cardboard on the site, where the cardboard is needed, in particular on or at the site of a system for automatically forming packaging boxes, EP 3 050 809 A1 discloses a method and an apparatus, in which the open side of a single-faced corrugated cardboard, i.e. cardboard comprising a corrugated layer and a first flat layer, is “closed” by attaching on-site a so called “closing layer”, i.e. a second flat layer to it and hence sandwiching the corrugated layer between the first flat layer and the second flat layer. According to EP 3 050 809 A1, at least one of the corrugated layer or the second flat layer has adhesive properties that can be activated on-site, e.g., by removing a protective cover, by contacting it with the other layer, or by subjecting the respective layer to pressure, heat etc.
Cardboard created on-site and hence having no unwanted folds can advantageously be used, e.g., in a machine such as the one disclosed in WO 2014 117 817 A1, which allows creating a fully custom sized box, i.e., a box, of which width, length and height are adapted to the respective content of the box.
However, the hitherto known methods and apparatus for creating cardboard on-site always employ only one type of single-faced corrugated cardboard to which a closing layer, i.e., a second flat layer, is attached. While such closing layer may add a quality like water repellency, the strength and stiffness of a box to be folded from the cardboard created on-site is mainly determined by the type of single-faced corrugated cardboard used for creating the double-faced cardboard. Thus, while the cardboard created with the known methods and apparatus might be too weak for folding stable boxes for certain arrangements of one or more item(s) to be shipped, it might be stronger (and hence generally heavier, more material consuming and more expensive, both, in production and in postage) than necessary for other arrangements.